The present invention is directed to a compressively resistant and resilient fibrous nonwoven web which is suitable for a number of uses including, but not limited to, personal care absorbent articles. Other uses for the material of the present invention are also contemplated to be within the scope of the present invention.
Personal care absorbent products such as diapers, training pants, incontinence devices, feminine hygiene products, bandages and the like are designed to absorb body fluids including blood, urine, menses and feces. In certain instances these products must be able to quickly absorb relatively large quantities of liquid, urine being an example, and still keep the wearer as dry and comfortable as possible. Typically, such personal care absorbent products will include a liquid permeable top sheet, a bottom sheet and an absorbent core disposed between the top sheet and the bottom sheet. The top sheet is usually made from some type of fibrous permeable nonwoven web such as a bonded carded web or a spunbonded web. The bottom sheet will typically be made from some type of material or laminate which is liquid impervious, and optionally, breathable.
The absorbent core is usually made from wood pulp fibers also referred to as "fluff" and can optionally include superabsorbent particles which are designed to absorb many times their own weight in liquid. When a child or adult urinates, the urine passes through the top sheet and is absorbed into the absorbent core below. A problem with the absorbent cores is that they are not very effective at quickly channeling liquid away to more remote parts of the absorbent structure. As a result, at least a part of the liquid retained in the crotch area may wick back to the top sheet which is usually in contact with the wearer's skin. This urine-soaked material is at the very least uncomfortable, inhibits air flow to the skin and may possibly exacerbate any skin conditions which are present.
Attempts have been made to alleviate these problems by placing additional materials in between the top sheet and the absorbent core. These materials have been referred to as transfer layers whose function it is to take up the liquid delivered to it through the top sheet and then transfer it to the absorbent core. One such material is currently used by the assignee of record in its Huggies.RTM. Ultratrim and Supreme diapers. The transfer layer consists of a 50 gram per square meter through air thermally bonded carded web made from a weight percent blend of 60 percent 6 denier polyester staple fibers and 40 percent polyethylene sheath/polypropylene core 3 denier bicomponent fibers. The resultant web has a thickness of 80 mils (2.03 millimeters). While this material has helped in reducing wetness against the skin, improvements are still desirable.
Ideally, such a transfer layer would readily take in liquid to get it away from the skin. It would give up the same liquid to other components in the diaper or other personal care absorbent product so that it would not stay wet and it also would be able to separate the skin and top sheet from the rest of the absorbent system. Lastly, the material would be able to maintain the separation under a variety of conditions.
Current transfer layers are able to take in fluids to get them away from the skin and then pass them away to the absorbent core. A problem they have however is that they are not effective at maintaining separation during heavy compression cycles such as when a baby or adult is sitting or sleeping. There is therefore a need for a compressively resistant and resilient material which will adequately separate the wearer from the fluid laden absorbent core. A supposed solution would simply be to "beef-up" the existing materials to achieve these objectives. However, simply increasing basis weight can adversely impact the ability of the material to take in fluids and then readily give them up the absorbent core. In addition, if the material becomes too thick, it will make the end product too big and bulky especially when considering the small dimensions of a baby in the perineal area of the torso. Consequently, these properties must be combined and optimized preferably in a single material. The present invention is directed to such a material as will become more apparent from the following description, drawings and claims.